Detalhes bibliográficos
| Autor(a) principal: |
Vieira, Lígia Maria Mendonça |
| Data de Publicação: |
2012 |
| Tipo de documento: |
Tese
|
| Idioma: |
por |
| Título da fonte: |
LOCUS Repositório Institucional da UFV |
| Texto Completo: |
http://locus.ufv.br/handle/123456789/218
|
Resumo: |
Economic and environmental aspects have motivated the chemical industry to replace "classical" processes of oxidation, which are based on salts of chromium and manganese, and results in large amount of effluents and toxic waste by catalytic systems. The use of catalysts is clean technology that reduces costs, the number of steps, the amount of by-products and consequently the environmental impact. Accordingly, catalysts based on transition metals and the use of hydrogen peroxide as oxidizer has been considered as an alternative quite interesting. This work had as main objective to investigate the efficiency of palladium catalysts in selective oxidation of monoterpenes by hydrogen peroxide in homogeneous phase. The effects of main parameters of reaction in the conversion and selectivity of oxidation have been assessed, such as the nature of the palladium catalyst and terpenic substrate, the effect of solvent and temperature, as well as the effect of concentrations both, oxidant and catalyst. The oxidation of β-pinene resulted in the formation of majority alílic oxidation products: pinocarvone, myrtenol, pinocarveol, epoxy-β-pinene, methoxy-mirtene and myrtenoic acid. In general, virtually complete conversions of the substrate into oxidation products with selectivity near 100%, have been obtained in the reactions, being PdCl2 and Pd (OAc)2 the more efficient catalysts. In reactions with the 3-carene primary oxidation products formed were the 3-carenol, 3-carene-5-one and 3-carene-2-one with maximum selectivity reached 78, 42 and 65% respectively, and conversion of 75%. However, in general a mixture of others oxidation products were also obtained. The oxidation of camphene resulted in the formation of unedited oxidation products nominated β-Keto-acid pseudopinene, β-Keto-methoxy-pseudopinene, β-Keto-hydroxy-pseudopinene and hydroxy-camphene acid that were separated and characterized by spectroscopic methods. In addition to these, there were also obtained the products epoxy-camphene, camphene-glycol and aldehyde-camphene. The largest conversions and oxidation products selectivity occurred in methanol. |